Reddit reviews Learning Unix for OS X: Going Deep With the Terminal and Shell
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>What exactly do you mean by watching it to see CPU? I'm quite familiar with Top -u, but is there a way to view just that processes CPU? I kind of want to watch it through my computer while browsing and see what happens.
You need to get its PID first. My favorite way to do that is with System Status from the App Store, which lists running processes with PIDs (although you can't kill them or anything).
Then use:
top -pid PID
To see just that process's stats.
>Does that Jetslammed tweak have anything related to this or help this?
Jetslammed can change a launchdaemon's HighWaterMark RAM limit, the limit of sustained RAM usage at which Jetsam automatically kills the daemon.
http://newosxbook.com/articles/MemoryPressure.html
The HWM can also be changed manually, but, in the end, it doesn't really help that much unless a daemon is only dying due to exceeding its HWM.
It can still be killed for other reasons if the system is low on memory.
It doesn't actually keep discoveryd from EVER being killed, so it doesn't really solve the issue of very large hosts (>300 KB) files causing random website disconnects due to discoveryd dying, leading to DNS failure.
It really just fixes it so that you can have Wifried and a small ad blocking hosts file at the same time since Wifried + even a small hosts file (like Light UHB) will cause discoveryd to use about 9-10 MB, exceeding the 8 MB HWM limit for a long period of time, causing discoveryd to be automatically killed, causing Wifried to re-initialize Wifi, causing random Wifi disconnects, which is even more problematic than even a DNS failure.
Wifried with Jetslammed raises the HWM for discoveryd to 12 MB from 8 MB, preventing the HWM killing of discoveryd with Wifried + small ad blocking hosts file. A large hosts file will exceed even this new limit, but, in that case, where discoveryd uses 20 MB or more, it will be killed by the system anyway for other reasons not related to the HWM.
>So do I have the correct Light UHB? Is that the one you use? I guess I might try reinstalling and maybe see. Haven't had an issue since its crash and (haven't checked today) haven't seen it anywhere near the top when running "top".
I use Light Untrusted Hosts. I've watched discovery's PID for about a month now. It's not being jetsam killed anymore even if I load a LOT of tabs and really stress it out. It never goes over 8 MB (the HWM) for any sustained period of time (even 8 MB requires A LOT of DNS activity), and never reaches enough RAM usage that the system would think to kill it to free memory (10-20 MB). Gamed (the GameCenter daemon) uses more memory than discoveryd with Light UHB . . .
>-unrelated- I love learning about all this stuff and your fountain of knowledge so far. Mind if I asked where you learned so much? I've been learning a lot about daemons lately, especially locationd and backboardd. I'm just curious as to where I can learn more about this stuff, learn how to read crash logs as so far it's just from the little experience I have, etc. I just can't find any good resources..
I've used OS X since it was in beta, and iOS is secretly just OS X in disguise with a TouchUI, a few processes missing, and a few processes added.
This book has been helpful to me in understanding jailbreaking, although it is a bit dated:
http://www.amazon.com/iOS-Hackers-Handbook-Charlie-Miller/dp/1118204123
Also a bit dated, but you may like it if you have a Mac:
http://www.amazon.com/Learning-Unix-OS-Going-Terminal/dp/1449332315/ref=sr_1_1?s=books&ie=UTF8&qid=1418694791&sr=1-1&keywords=OS+X+unix
This wiki is also good. Many devs post on it:
https://theiphonewiki.com/wiki/Main_Page